Electromagnetic control device



1959 G. E. DIETZ ET AL 2,869,049

ELECTROMAGNETIC CONTROL DEVICE 2 Sheets-Sheet 1 Filed April 15, 1954 Jan. 13, 1959 G. E. DlETZ ET AL 2,869,049

ELECTROMAGNETIC CONTROL DEVICE 2 Sheets-Sheet 2 Filed April 13, 1954 INVENTOR. Ger-add 5. Q1165; Q'doZph J: Hiya/=2 BY cletyvvt M MLMc/Z fit? s E 2,869,049 ELECTRGMAGNETIC corvrnor. nsvrcn Gerald E. Dietz and Adolph J. Hilgert, Milwaukee, Wis, assignors to B350 Inc., Milwaukee, Wis a corps of Wisconsin Application April 13, 1954, Serial N 422,927 17 Claims. (Cl. 317-=166) This invention relates to improvements in direct-acting electromagnetic control devices operable on small amounts of power, for example thermoelectric power. More particularly, the invention relates to an electromag etic device of the type which comprises a coil disposed within a magnetic field in which the lines of force extend radially with respect to said coil, axial movement being imparted to said coil in response to the flow therethrough of an electric current, for example a thermoelectric current, said movement being effected by mutual repulsion of the field of said coil and said magnetic field. In a device of this type the coil is actuated with maximum force at the beginning of its movement, such operation being in contrast with the operation of devices which exert a relatively small force at the beginning of the stroke and exert maximum force at the end of the stroke. An example of the latter type device is the conventional solenoid.

With the above in mind, it is a general object of the present invention to provide an improved electromagnetic control device, having an electromagnetic operator and a control member actuated thereby, the force exerted by said operator being matched to the resisting force exerted by the control member. More specifically, the

device provides an operator havin maximum force at the beginning of its stroke matched to a load which presents maximum resistance at the beginning of its stroke, said matching alfording maximum efficiency and avoid ing excess power in the operator, thereby making it possible for an operator powered by small amounts of power, for example thermoelectric power, to do usable work.

Another object of the invention is to provide an improved control device having improved efficiency by virtue of a novel magnetic structure which not only prevents flux leakage external thereto, but also provides for utilization of substantially all of the magnetic flux.

Another object of the invention is to provide a control device of the aforementioned character in which the magnetic structure includes an improved permanent magnet and an associated air gap, said magnet being polarized in a novel manner and is so positioned with respect to said air gap that substantially all of the permanent magnet flux must flow across said air gap and be available for use therein.

Another object of the invention is to provide an improved electromagnetic control device of the moving coil type wherein the magnetic structure permits the use of a relatively small diameter coil, thereby reducing the length and hence the resistance of said coil for a given number of turns. The aforementioned low coil resistance is of particular value when the improved device is operated on power from a thermoelectric generator or other small power source, said lower resistance permitting substantially increased current flow in the thermoelectric circuit and correspondingly increased work output.

Another object of the invention is to provide an improved control device wherein the moving coil is provided with substantially friction free guiding means.

Another object of the invention is to provide, in a coninc trol device of the class described, coil guiding means in the form of looped members of metallic band material which is arcuate in transverse cross-section, said looped members also providing low resistance connections to the moving coil.

Another object of the invention is to provide, in a control device of the class described, adjustable means asscciated with the coil guiding means for impressing an axial bias on the movable coil.

Another object of the invention is to provide an improved control device of the character described in which rolling action is imparted to the looped coil guiding members on axial movement of the coil, said rolling action being utilized to impart tilting movement to a mercury switch.

Another object of the invention is to provide means for transmitting axial movement of the coil directly to a device to be controlled, for example a valve, said means comprising a force transmitting linkage which includes an energy storing member.

Other and further objects of the invention will become apparent as the description proceeds, reference being had to the accompanying drawings illustrating two embodiments of the invention, and in which like charactors of reference indicate the same parts in all of the views.

In the drawings:

Figure l is a vertical sectional view taken through one form of the improved control device, a thermoelectric circuit for supplying current to said device being shown semidiagrammatically;

Figure 2 is a fragmentary semi-diagrammatic verticalsectional view of the magnetic structure of the improved control device taken approximately along the line 2-2 of Figure 1 and provided with arrows illustrating the permanent magnet flux paths therein;

Fi ure 3 is a side elevational view of the improved control device as viewed from the right in Figure l; and

Figure 4 is a fragmentary vertical sectional view of another form of the improved control device illustrating the use of connections for actuating a valve.

The control device selected for illustration of the invention in Figures 1 and 3 takes the form of a relay. Referring to Figure 3, the invention comprises a frame hav ing opposite elongated side bars 5 and 6, which may be channel-shaped in transverse cross-section, said frame having transverse opposite end members 7 and 3. The end member 7 is preferably made of electrical insulating material, whereas the member 8 may take the form of a metal plate. A pair of transverse brackets 1d and are connected to the side bars 5 and 6 support a magnetic structure 9.

As shown most clearly in Figures 1 and 2, the magnetic structure 9 comprises a magnetically permeable hollow casing which, in the illustrated embodiment, is made up of a pair of coaxial generally cup-shaped members 12 and connected by a coaxial annular member 14 having a cylindrical inner surface 15 of reduced diameter. The magnetic structure 9 is provided with a coaxial cylindrical core 16 which, in the illustrated embodiment, includes a cylindrical permanent magnet section 17 spaced coaxially within and axially coextensive with the cylindrical inner surface 15 to provide an annular cylindrical air gap 21 therewith. The core 16 also includes means affording flux conducting connections between the opposite end portions of the permanent magnet core section 17 and the adjacent cup-shaped casing members 12 and 13, said means comprising a pair of magnetically permeable cylindrical end sections 18 and 19 as shown. For ease of assembly and for positive retention of the core 16 in proper operative position within J11 as shown and o) the casing 9, the magnet 17 is formed with concave end faces, and the sections 18 and 19 are formed with convex end faces which interfit with the end faces of the permanent magnet 17 and with matching recesses in the cupshaped members 12 and 13 as shown. it is apparent that securement together of the casing members T3, and 14, as by screws 20, not only retains said members in assembled relationship, but also retains the sections of the core to in operative position.

The permanent magnet core section 17 is polarized in a novel manner, said magnet having like polarity its opposite ends, for example south as shown in Figure 2, and having an oppositely polarized central portion, for example north as shown in Figure With the illus trated polarity, it is apparent that flux flows as indicated by the arrows in Figure 2, out of the ends of the permanent magnet ll'7, through the core sections 18 and iii, through the cup-shaped casing members 12 and it?) to the annular casing section 14, and thence radially inwardly across the air gap 21 back to the central portion of the permanent magnet section 17. It is obvious, of course, that if the polarity of the magnet section 17 is reversed, the flux flow is also reversed. By having the magnet section 17 polarized in the manner described and disposing said magnet within the annular air gap as shown, all flux leaving the ends of said magnet must flow across the air gap 21 in order to return to the central portion of said magnet. Enclosure of the magnet section within the casing formed by the sections 12, 13 and 14- provides a shield which prevents the leakage of any flux external to said casing. it is apparent, therefore, that not only is external flux leakage prevented, but all of the flux is made available for use by virtue of the fact that it must flow across the air gap Zll.

Positioned coaxially within the annular air gap 21 is a coil 22 of relatively heavy, low resistance wire. The coil 22 is freely movable in the air gap 21 and is provided with novel guiding and electrical connection means which will now be described.

A pair of U-shaped brackets 23 and 24 of electrical insulating material are adiustably mounted on the frame end plate being fixed thereto by means of screws 25 and 26 which extend through elongated transverse slots 27 and in said plate as shown in Figure l. The brackets 23 and carry pivot screws 29 and 3d respectively, on which are mounted elongated arms 31 and 32, the upper ends of which may take the form of rectangular loops as shown most clearly in Figure 3. The trans verse frame end bar member 7 is provided with depending lugs 33 and 34 (see Figure l) to which are pivotally connected internally threaded fittings 35 and 36. A pair of elongated s "ews 37 and 38 extend loosely through suitable apertures in the upper ends of the pivoted arms and 32, and are hreaded into the fittings 35 and ed as shown, said screws being provided with lock nuts 39 and The position of the arms 31 and 32 is determined by nuts 41 and 4-2 on each of the screws 37 and said nuts clampingly engaging said arms as shown.

The magnetic shell 9 is formed with two diametrically opposite, axially extending slots or cut-away portions 43 and (Figures 1 and 3) having a width to receive the arms 31 and 32 without being contacted thereby. A pair of looped members 45 and 46 are fixed to the inner surfaces of the arms 31 and 32, as by being clamped to said arms by elongated bars 47 and 43, said bars being fix d to said arms by screws .9. The bars and and looped members and aligned with the arms and 32 and are also aligned with the core To, said looped members and bars also being positioned within the casing cut-away portions 43 and 44 as shown.

The looped members E5 and are preferably made of metallic band material which is normally concavoconvex in transverse cross-section, said band having a flat cross-sectional shape when bent longitudinally.

Cir

4 Within the cut-away portions 43 and 4d, the looped members 45 and are fixed, as by riveting, to a pair of elongated plate members 5% and 51 which are substantially flat and are parallel with the axis of the coil 22 and core 16. The plates 59 and 51 are disposed on diametrically opposite sides of the coil 22 and are fixedly connected thereto, one end of said coil being connected in circuit with the plate 56, as at 52, and the other end said coil being connected in circuit with the plate 51,

as at It is apparent that fixation of the looped mems and 46 to the arms 31 and 32 and to the plates and 51 in the manner described provides each of said looped members with straight inner and outer extents.

Since the structure so far described is symmetrical at out the axis of the core 16, the looped members 45 and provide a substantially friction free guiding means for the coil which permits free axial movement of said coil in the air gap while preventing any misalignment of said coil with the axis of the core Axial movement of said coil imparts a rolling action to the looped members and 4G which members normally present no substantial resistance to the movement of said coil. As will hereinafter appear, however, an axial bias can be impressed upon the coil 22 by the looped members 45 and es.

The looped members and 56 not only provide the aforementioned friction free guidance for the coil 22, but also serve as low resistance connector means between the coil 22 and an external electrical circuit. To this end, the frame end plate 8 is provided with an externally threaded tubular fitting which insulatably carries a terminal connector 55 having a terminal tip 56 exposed within an end socket 57. A conductor 58 connects the arm 31 in circuit with the terminal connector 55, and a conductor 59 connects the arm 32 in circuit with the fitting 5-4 Since the looped members 45 and 46 are clamped to the arms 31 and 32, this clamping engagement also effects an electrical connection between said members and said arm.

The coil 22 may be connected in circuit with a source of small electric power, for example a thermoelectric generator 6h, by means of a conductor s1 connecting one terminal of said generator to the fitting The other terminal of the generator on is connected in circuit with th terminal tip 56 by a conductor 62 in which may be interposed a circuit-controlling device 63. The device 63 may take the form of a thermostat having coacting relatively movable contacts 64 and 65 encapsulated within an hermetically sealed expansible and contractible enclosure 66, for example a bellows. The generator 66 may be subject to the heat of a pilot burner 67 which forms part of a fluid fuel burning apparatus including a main burner 68 with which said pilot burner coacts.

in operation of the improved control device, the flux from the permanent magnet 17 continually flows in the manner shown in Figure 2, spanning the air gap 21 and hence cutting across the coil 22. When the thermostat 63 calls for heat and engages the contact 65 with the contact 64, thermoelectric current from the generator flows through the coil 22 and creates a field which reacts with the flux flowing across the air gap 21 in a man her to cause the coil to be lifted from the solid line position of Figures 1 and 2 to the dot and dash line position thereof. This action depends upon the well known motor principle by which a conductor positioned in a magnetic field is moved in a direction normal to the d':ection of the lines of force of said field. When the thermostat 63 no longer calls for heat and thermoelectric circuit is broken by disengagement by the contacts 64 and 65, the coil 22 returns by gravity or other suitable bias to the solid line position thereof as shown in Figures 1 and 2.

In the form of the invention illustrated in Figure l, the rolling movement imparted to the looped members and 46 by axial movement of the coil 22 is utilized to actuate a mercury switch 69. The switch 69 is carried by a friction clip 70 which is fixed to the upper end of the looped member 45 as shown in Figure 1, and said switch is provided with a pair of contacts 71 and 72 which coact with a pool of mercury 75. Flexible conductors 73 and 74 connect the contacts 71 and 72 in circuit with terminals 76 and 77 (Figure 3) carried by the insulating frame end bar 7. The friction clip 70 is fixed to the looped member 45 is such a manner that when the coil 22 is in the lowered solid line position thereof, the mercury switch 69 is tilted as shown, so that the mecury 75 is out of engagement with the contacts 71 and 72 and the circuit therebetween is open. However, on movement of the coil 22 to its raised dot and dash line position, the rolling movement of the looped member 45 to its dot and dash line position tilts the mercury switch to the dot and dash line position in which the mercury 75 completes the electrical circuit between the contacts 71 and 72. form of the invention shown in Figures 1 and 3 functions as a relay. The terminals 76 and 77 provide means for connecting the contacts 71 and 72 into the circuit to be controlled by the aforementioned relay.

An axial bias can be impressed on the coil 22 by the looped member 45 and 46 by positioning the arms Sit and 32 in a manner to exert opposing lateral stresses on end portions of the looped members 45 and 46. The arms 31 and 32, as disposed in Figure 1, converge downwardly so that lateral compressive stresses are exerted on the lower ends of the looped members 45 and 46. As a result, the looped members exert an upward bias on the coil 22 which neutralizes at least a part of the gravity bias resulting from the Weight of the coil and of the parts connected thereto and supported by the looped members 45 and 46. The amount of axial bias can be readily adjusted by varying the spacing between or the angularity of the arms 31. This is accomplished by adjusting the position of the brackets 23 and 24 or by moving the upper ends of the arms 36? and 31 along the screws 37 and 33. In the absence of the need for a counterbalancing bias, the arms 31 and 32 may be positioned substantially parallel by moving the brackets 23 and 24 outwardly, and by moving the upper ends of the arms 31 and 32 inwardly along the screws 37 and 38.

Figure 4 illustrates another form of the invention in which the axial movement of a coil (not shown) similar to the coil 22 is utilized for actuation of a device controlled thereby, for example a valve 78. In Figure 4,

the parts indicated by primed reference characters may be identical with parts indicated by the same reference characters unprimed in Figure 1. In Figure 4, the plates and 51 are extended and are pivotally connecte to a yoke 81. A force transmitting shaft 82 is pivotally connected to the yoke 81 and extends through a suitable aperture in the frame end bar 7' to a pivotal connection with the arm 80 of the valve 73. The force transmitting shaft 82 may include an energy storing spring 83. It is apparent that on axial upward movement of the plates 50' and 51, the valve member 79 of the valve 78 is moved ofi its seat. Return of the plates 5d and 51" to their normal position, returns the valve member 79 to its seat.

The structure of the improved control device is particularly Well adapted for operation on thermoelectric power. This is true for a number of reasons, one of which is that the entire coil circuit is made up of lowresistance elements, the looped members 4-5 and 46 eliminating the need for flexible coil leads which are of inherently high resistance. The particular magnetic structure .of the improved control device further enhances the efficiency thereof by virture of the fact that the per manent magnet flux flows from the ends of the permanent magnet 17 and through the sections 16 and 19. Since each of the core sections 16 and 19 needs to conduct It is apparent, therefore, that the only half of the magnetic flux, these sections and the core 17 can be of relatively small diameter. This permits a corresponding reduction in the diameter of the coil 22 the effect of which is to reduce the over-all length of the coil 22 for a given number of turns. This reduced coil length substantially reduces the amount of resistance of said coil and correspondingly increases the amount of thermoelectric current which can flow through said coil for actuation thereof.

The specific illustrations and corresponding description are used for the purpose of disclosure only, and are not intended to impose unnecessary limitations on the claims or to confine the patented invention to a particular use. Various changes and modifications may be made without departing from the spirit of the invention, and all of such changes are contemplated as may come within the scope of the claims.

What is claimed as the invention is:

1. In an electromagnetic device: a magnetic core having opposite end portions and an intermediate permanently magnetized cylindrical section, said section having like polarity at its ends and having an oppositely polarized intermediate portion; and a magnetically permeable frame substantially completely surrounding said core to prevent substantial leakage of magnetic flux therebeyond and having spaced portions in flux-conducting engagement with the end portions of said core, said frame also having an intermediate portion having a cylindrical inner surface of reduced diameter coaxially surrounding and axially coextensive with said permanently magnetized core section to provide therewith a radial air gap, said permanently magnetized core section establishing magnetic flux flow through said core and frame and across said air gap, the polarity of said permanently magnetized core section and the disposition thereof Within the cylindrical inner surface portion of the frame causing substantially all of the flux produced by said core section to flow in said air gap.

2. in an electromagnetic device: A magnetic core having opposite end portions and an intermediate permanently magnetized cylindrical section, said section having like polarity at its ends and having an oppositely polarized intermediate portion; and a magnetically permeable frame substantially completely surrounding said core to prevent substantial leakage of magnetic flux therebeyond and having spaced portions in flux-conducting engagement with the end portions of said core, said frame also having an intermediate portion having a cylindrical inner surface of reduced diameter coaxially surrounding and axially coextensive with said permanently magnetized core section to provide therewith a radial air gap, said permanently magnetized core section establishing magnetic flux flow through said core and frame and across said air gap; a cylindrical coil coaxially surrounding said permanently magnetized core section and movable in said air gap, the polarity of said permanently magnetized core section and the disposition thereof within said radial air gap and said coil causing substantially all of the flux produced by said co rle section to flow in said air gap for coaction with said co:

3. In an electromagnetic device: A magnetic core having opposite end portions and an intermediate permanently magnetized cylindrical section, said section having like polarity at its ends and having an oppositely polarized intermediate portion and a magnetically permeable casing substantially completely enclosing said .core to prevent substantial leakage of magnetic flux therebeyond and having opposite end Wall portions in flux-conducting engagement with the end portions of said core, said casing also having an intermediate portion extending radially inwardly toward said core and having a cylindrical inner surface coaxially surrounding and axially coextensive with said permanently magnetized core section to provide therewith a radial air gap, said permanently magnetized core section establishing magnetic flux flow through said core and casing and across said air gap; a cylindrical coil coaxially surrounding said permanently magnetized core section and movable in said air gap, the polarity of said permanently magnetized core section and the disposition thereof within said radial air gap and said coil causing substantially all of the flux produced by said core section to flow in said air gap, enclosure of said core and coil within said casing preventing any substantial flux leakage externally thereof.

4. In an electromagnetic device: A frame; a magnetic core having opposite end portions and an intermediate portion; a magnetically permeable casing on said frame substantially completely enclosing said core to prevent substantial. leakage of magnetic flux therebeyond and having opposite end wall portions in flux-conducting engagement with the end portions of said core, said c.- having cutaway portions and also having an intermediate sortion extending inwardly toward and. coaxially surrounding said intr tediate core portion and providing th ewith a radial air gap; flux-generating means establishi magntic flux flow in core in one direction between said intermediate core portion and one core end portion and in the opposite direction between said intermedit e core portion and the other core end portion, said means also causing said magnetic flux to flow through said casing and across air gap, the disposition of said iuterm d core portion Within said radial air gap causi substa tially all of the flux produced by said fluxgenera meals to flow in said air gap; a cylindrical coil coaxially surrounding said intermediate core portion and movable axially in said air gap when energized; a pair of looped members of flexible low resistance metallic band material normally concave-convex in transverse cross-section, said looped members having portions dis-- posed in the cutaway portions of said casing on opposite sides of said coil and aligned therewith, said looped members each having an inner extent fixed to said coil and in circuit with a seperate end thereof, each or" said looped members also having an outer extent fixed to said frame; and terminal means in circuit with said outer extents, said looped members ai o-rding low resistance electrical connections between said terminal means and said coil and also affording substantially friction free guidance for said coil during axial movement thereof, said looped members assuming a rolling action during said coil movement.

5. In combination: rectilinearly reciprocatable member; and a pair of looped members of flexible band material normally concavo-ccnvex in transverse crosssection, said lco' "d members being disposed on opposite sides of said .Htllinearly movable member and aligned therewith, said looped members each having a substantially straight inner fixed to said rectilinearly movable member and having a substantially straight outer extent extending in the some general direction as said inner xtent and fixed to a flat supporting surface, Wherefore reciprot a rolling to said looped members, the latter providing substantially friction tree guidance for said reciprocatable member; and means for biasing said reciprocatable member in one direction of its reciprocating movement, said means comprising mechanism applying lateral stresses on corresponding end portions of the straight extents of said looped members, thereby causing convergence of stressed ends of the straight inner and outer extents of: each looped members and biasing of the reciprocatable member in the direction toward the opposite ends or" said straight extents.

6. in an electromagnetic device: a magnetic core having opposite end portions and an intermediate portion, a magnetically permeable casing substantially completely enclosing said core to prevent any substantial flux leax age therebeyond, and means allording flux conducting connections between the end portions of said core and spaced portions of said casing, said casing also having an intermediate portion coaxially surrounding and axially coextensive with said core and providing therewith a radial air gap, said core being magnetically polarized with one polarity at its end portions and the opposite polarity at its intermediate portion, the disposition of said core coextensively within said radial air gap causing substantially all flux flow to and from said core to How in said air gap.

7. in an electromagnetic device: a magnetic core hav ing opposite end portions and an intermediate portion, a magnetically permeable casing substantially completely enclosing said core to prevent any substantial flux lea age therebeyond, means aiiording flux conducting connections between the end portions of said core and spaced portions of said casing, said casing also having an intermediate portion coaxially surrounding and axially coextensive with said core and providing therewith a radial air gap, and a cylindrical coil coaxially surrounding said core and movable in said air gap, said core being magnetically polarized with one polarity at its end portions and the opposite polarity at its intermediate portion, the disposition of said core coextcnsively within said radial air gap causing substantially all flux flow to and from said core to flow in said air gap for coaction with said coil.

8. ln electromagnetic device: a magnetic core having opposite end portions and an intermediate portion, a magnetically permeable casing substantially completely enclosing said core to prevent any substantial flux leakage therebeyend, means aitording flux conducting connections between the end portions of said core and opposite end wall portions of said casing, said casing also having an intermediate portion extending radially inwardly toward said core, said intermediate casing portion being disposed in coaxial surrounding and axially coextensive relation with said core and providing therewith a radial air gap, said core being magnetically polarized with one polarity at its end portions and the opposite polarity at its intermediate portion, the disposition of said core coextensively within said radial air gap causing substantially all flux flow to and from said core to flow in said air gap.

9. In an electromagnetic device: permanent magnet core having opposite end portions of one polarity and an intermediate portion of the opposite polarity, a mag netically permeable casing substantially completely enclosing said core to prevent any substantial flux leakage therebeyond, means affording flux conducting connections between the end portions of said core and spaced portions of said casing, said casing also having an intermediate portion coaxially surrounding and axially coextensive with said core and providing therewith a radial air gap, the disposition of said core coextensively within said radial air gap causing substantially all flux flow to and from said core to flow in said air gap.

10. In combination, a rectilinearly reciprocatable member, a support, and substantially friction free guiding means for said member comprising a strip or" flexible band material aligned with the direction of movement of said member, said strip having a generally U-shaped portion having opposite legs respectively fixed to said member and suport, said legs being connected by a reversely bent extent, at least one of said legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to said strip during which the reverse bend in said strip moves therealong to cause shortening of: one of said legs by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg by generation of a substantially straight portion therein from said reversely bent portion.

ll. in combination, a rectilinearly reciprocatable member, support means and substantially friction free guiding means for member comprising a plurality of strips of flexible band material spaced equally about said memher and aligned with the direction of movement of said aseaoae member, each of said stripshaving a generally U-shaped portion having opposite legs respectively fixed to said member and support means, each of said pairs of legs being connected by a reversely bent extent, at least one of each of said pairs of legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to each of said strips during which the reverse bend in each of said strips moves therealong to cause shortening of one of said legs thereof by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg thereof by generation of a substantially straight portion therein from said reversely bent portion.

12. In combination, a rectilinearly reciprocatable member, a support having a surface generally parallel with the direction of movement of said member, and substantially friction free guiding means for said member comprising a strip of flexible band material aligned with the direction of movement of said member, said strip having a generally U-shaped portion having substantially parallel opposite legs respectivelyfixed to said member and said surface of said support, said legs being connected by a reversely bent extent at least one of said legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent por tion, whereby rectilinear movement of said member in one direction imparts a rolling action to said strip during which the reverse bend in said strip moves therealong to cause shortening of one of said legs by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg by generation of a substantially straight portion therein from said reversely bent portion.

13. In combination, a rectilinearly reciprocatable member, a support having a surface generally parallel with the direction of movement of said member, and substantially friction free guiding means for said member comprising a strip of flexible band material normally concave-convex in transverse cross section and aligned with the direction of movement of said member, said strip having a generally U-shaped portion having opposite legs substantially concavo-convex in transverse cross section and respectively fixed to said member and the surface of said support, said legs being connected by an extent which is reversely bent to render said strip substantially flat in transverse cross section at said bend, at least one of said legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to said strip causing movement of the reverse bend along said strip to cause shortening of one of said legs by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg by generation of a substantially straight portion therein from said reversely bent portion.

14. In combination, a rectilinearly reciprocatable member, a support having a plurality of surfaces equally spaced about said member and disposed generally parallel with the direction of movement of said member, and substantially friction free guiding means for said member comprising a plurality of strips of flexible band material each of which is normally concavo-convex in transverse cross section and is aligned with the direction of movement of said member, each of said strips having a generally U-shaped portion having opposite legs substantially concavo-convex in transverse cross section and respectively fixed to said member and one of the surfaces of said support, each of said pairs of legs being connected by an extent which is reversely bent to render said strip substantially flat in transverse cross section at said bend, at least one of each of said pairs of legs having a substantially straight portion extending between the fixed connection thereof and the respective reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to each of said strips causing movement of each of the reverse bends along the respective strip to cause shortening of one of the legs thereof by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg thereof by generation of a substantially straight portion therein from said reversely bent portion.

15. in combination, a rectilinearly reciprocatable member, a support having a surface generally parallel with the direction of movement of said member, substantially friction free guiding means for said member comprising a strip of flexible band material normally concavo-convex in transverse cross section and aligned with the direction of movement of said member, said strip having a generally U-shaped portion having opposite legs substantially concavo-convex in transverse cross section and respectively fixed to said member and the surface of said support, said legs being connected by an extent which is reversely bent to render said strip substantially flat in transverse cross section at said bend, at least one of said legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to said strip causing movement of the reverse bend alongsaid strip to cause shortening of one of said legs by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg by generation of a substantially straight portion therein from said reversely bent portion, and a position sensitive mercury switch fixed to said reversely bent extent for tilting thereof from one position to another by rolling action of said strip in response to movement of said reciprocatable member in said one direction.

16. In combination, a rectilinearly reciprocatable member, a support having a surface generally parallel with the direction of movement of said member, substantially friction free guiding means for said member comprising a strip of flexible band material normally concavo-convex in transverse cross section and aligned with the direction of movement of said member, said strip having a generally U-shaped portion having opposite legs substantially concavo-convex in transverse cross section and respectively fixed to said member and the surface of said support, said legs being connected by an extent which is reversely bent to render said strip substantially flat in transverse cross section at said bend, at least one of said legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion, whereby rectilinear movement of said member in one direction imparts a rolling action to said strip causing movement of the bend along said strip to cause shortening of one of said legs by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg by generation of a substantially straight portion therein from said reversely bent portion, a valve, and force transmitting linkage connecting said valve to said reciprocatable member.

17. In an electroresponsive device, in combination, a rectilinearly reciprocatable coil, support means, substantially friction free guiding means for said coil comprising a pair of strips of flexible low resistance metallic band material equally spaced about said coil and aligned with the direction of movement of said coil, each of said strips having a generally U-shaped portion having opposite legs respectively secured to said coil in electrical continuity therewith and to said support means, each of said pairs of legs being connected by a reversely bent extent, at least one of each of said pairs of legs having a substantially straight portion extending between the fixed connection thereof and said reversely bent portion,

aeeaoae whereby rectilinear movement of said coil in one direction imparts a rolling action to said strips during which the reverse bend in each of said strips moves therealong to cause shortening of one of said legs thereof by flexing of said substantially straight portion to form part of said reversely bent portion and simultaneous lengthening of the other leg thereof by generation of a substantially straight portion therein from said reversely bent portion, and terminal means in circuit With those legs which are secured to said support means, said strips thereby affording low resistance electrical connections between said terminal means and said coil during movement of the latter.

References Cited in the file of this patent UNITED STATES PATENTS Davis Aug. 4, Day Dec. 7, Carton Apr. 13, Ray Nov. 25, Neild May 2, Roberton Sept. 9, 

